Preparation And Modification Of Nb₂O₅ Anode Material For Hybrid Supercapacitor

In this paper,NbCl₅,NH₄F and HO₂CCO₂H·2H₂O were used as raw materials to prepare Nb₂O₅ anode material with spherical nanostructured structure by hydrothermal method.The reaction conditions?NH₄F concentration,reaction time and reaction temperature?were optimized.TiO₂ nanoparticles were coated on the surface of synthetic Nb₂O₅ samples by in-situ dipping and hydrolyzing method to obtain Nb₂O₅@TiO₂composite materials.The electrochemical properties of Nb₂O₅ were improved.The results show that the samples obtained by changing the NH₄F concentration?0.05 M,0.1 M,0.15 M and 0.2 M?in the hydrothermal reaction are still Nb₂O₅.Comparison of the morphology and electrochemical properties of the samples,when the concentration of NH₄F was 0.15 M,the morphology of Nb₂O₅ samples was the best.When the current density is 0.2 A g^-1,the first discharge capacity of the Nb₂O₅ is 255.062 mAh g^-1,and the retention rate after 50 cycles was 83.28%.The discharge time of the hybrid supercapacitor of Nb₂O₅ was 1095 s,the discharge specific capacity is 27.278 F g^-1.The samples obtained by changing the reaction temperature?160?,170?,180?and 190??of the hydrothermal reaction were still Nb₂O_5.Comparison of the morphology and electrochemical properties of the samples,when reaction temperature was 170?,the morphology of Nb₂O₅ samples was the best.When the current density is0.2 A g^-1,the first discharge capacity of the Nb₂O₅ is 243.481 mAh g^-1,and the retention rate after 50 cycles was 63.34%.The discharge time of the hybrid supercapacitor of Nb₂O₅was 1105 s,the discharge specific capacity is 23.701 F g^-1.The samples obtained by changing the reaction time?4 h,8 h,12 h,18 h and 20 h?of the hydrothermal reaction were still Nb₂O_5.Comparison of the morphology and electrochemical properties of the samples,when reaction time was 18 h,the morphology of Nb₂O₅ samples was the best.When the current density is 0.2 A g^-1,the first discharge capacity of the Nb₂O₅ is 243.481 mAh g^-1,and the retention rate after 50 cycles was66.78%.The discharge time of the hybrid supercapacitor of Nb₂O₅ was 1105 s,the discharge specific capacity is 24.201 F g^-1.The electrochemical performance of Nb₂O₅@TiO₂ composite material lithium ion battery shows that when the current density is 0.2 A g^-1,the first discharge capacity of Nb₂O₅@TiO₂ is 240.367 mAh g^-1,and the retention rate after 50 cycles was 73.56%;The discharge time of the hybrid supercapacitor of Nb₂O₅@TiO₂ was 1125 s,the discharge specific capacity is 23.701 F g^-1.The highest energy density is 30.73 Wh kg^-1 and the power density is 1006.8 Wkg^-1.Compared with Nb₂O₅ anode material,Nb₂O₅@TiO₂composite has better electrochemical performance,high capacity retention rate and smaller charge transfer resistance of Faraday reaction.